DESC:FIELD OF THE INVENTION:
This invention relates to lubricating oil composition useful as universal tractor transmission oil (UTTO) with anti-chatter characteristics and having long drain potential.
BACKGROUND OF THE INVENTION:
In general, tractor lubricants are often referred to as Universal Tractor Transmission Oils (“UTTO”) or Tractor Hydraulic Fluids (“THF”). These lubricants provide performance required for hydraulics, transmission, gears, power take-off (“PTO”), and wet-brakes. In international and emerging markets, Super Tractor Universal Oil (“STUO” or “STOU”) lubricants are more widely used. STUO lubricants provide satisfactory lubrication of diesel and gasoline engines, in addition to providing the performance required for hydraulic, transmission, gear, PTO, and wet brake systems.
Universal tractor transmission oil (UTTO) is oil that can be used for multiple purpose such as wet brake, hydraulic, clutch, transmission system in farm tractors and earth moving equipment. Because of its multiple uses, UTTO can make machine maintenance easier. To meet these varied requirements, tractor lubricants must balance a large number of performance properties. UTTO and STUO tractor lubricants must provide anti-wear, provide load-carrying protection, and control frictional characteristics for equipment durability. In addition, the STUO tractor lubricants must maintain basic engine performance, without compromising the requirements of THFs for wet brake, PTO, transmission, gear, and hydraulics performance. Many of the additives used in tractor lubricant formulation are multifunctional and there is often a conflict generated between properties. To ensure that the tractor lubricant operates over a wide temperature range, it is necessary for the oil to be multi-grade. This requires the use of carefully chosen base oils combined with viscosity index improvers and pour point depressants to achieve the low and high temperature viscosity limits.
Now days most modern tractors are equipped with wet brakes because of the proven advantages of these. However, complaints about brake chatter found on agricultural and off-highway equipment continue to tarnish the benefits of such stopping devices. Naturally, many farmers are concerned by the braking noise and vibration.
Wet brakes are encased in the tractor’s axle housing for the reasons of which enables the brakes to be bathed in oil, which cools them under heavy loads and protects the brakes from harsh conditions such as dust, mud, water and moisture.
Dry brakes, on the other hand, are not encased in the tractor’s axle housing and therefore, the brakes operate dry (without oil) and are exposed to harsh conditions (dust, mud, water and moisture.) Now days there are a few OEMs (original equipment manufacturers) that produce tractors with a dry brake system, the majority of farm machinery is equipped with wet brakes. Farmers experience brake chatter when they hear loud squeaky noises from the braking system (when braking). Producers may also feel vibration of the tractor. This noise or chatter is a function of the oil/metal surface interaction, and the oil having an impact on the frictional characteristics of the braking surface. Since dry brakes are not immersed in oil, the brake chatter phenomenon does not occur. The brake chatter phenomenon can be caused by several factors including:
• High amount of fluid degradation.
• Large contamination of water in the fluids.
• Lack of sufficient lubrication of the brake couplings.
• Degradation of the brake friction material from high loads with extensive applications of heavy braking.
Heavy brake chatter can be very unpleasant (annoying) for the farmer and possibly damage the tractor if allowed to continue over a long period of time.
US3899432 covers the lubricating oil compositions useful both as hydraulic fluids and as lubricants in the transmissions and differentials of heavy machinery such as high-power output tractors. This lubricating oil composition is particularly useful in machinery using wet-type disc brakes physically located within the housing containing the lubricating oil composition.
EP0237804A2 covers the oil composition for manual transmissions which is used to lubricate manual transmissions [manual transmissions of FR (Front engine, Rear drive) automobiles and manual transaxle of FF (Front engine, Front drive) automobiles] of automobiles which include passenger cars, trucks, large-sized cars such as buses, and tractors.
US 4181619A covers the Hydraulic fluids containing the reaction product of benzotriazole and tricresyl phosphate are stabilized by the addition thereto of minor amounts of calcium dinonyl naphthalene sulfonate and calcium alkyl phenate. Such fluids and other oleaginous compositions containing the above-described novel additive combination are thus provided with good corrosion control, rust protection and improved cleanliness plus antiwear protection.
There was long felt need to provide lubricating oil composition useful as universal tractor transmission oil (UTTO) type lubricant with antichatter characteristics.
SUMMARY OF THE INVENTION:
The present invention provides a tractor lubricating oil composition having unique combination of additives and base oil of suitable viscosity which provides following characteristics over the existing prior arts:
1. Longer oil drain interval in the range of 800-1400 hrs without chatter in wet brakes.
2. Sufficient film thickness and excellent load carrying capability required for heavier load, low speed, high torque conditions
3. Superior water handling characteristics to protect from erosion and corrosion when contaminated with water
4. Higher viscosity stability over wide ranging mechanical condition.
5. Superior anti chatter characteristics without affecting braking efficiency
According to one embodiment of the present invention, a base oil combination comprising of 30-40 wt% solvent refined Group I mineral base oil of kinematic viscosity greater than 30 cSt at 100ºC and 60-70 wt% of hydrocracked Group II base oil of kinematic viscosity greater than 10.5 cSt at 100ºC.
According to another embodiment of the present invention, an additive composition comprising of a dispersant olefin copolymer (DOCP) as viscosity index improver in the range of 2-3 wt%, a universal tractor transmission oil (UTTO) additive system in the range of 4-10 wt%, a sulphur phosphorus additive component in the range of 0.5 to 2.5 wt%, and a monounsaturated omega-9- fatty acid in the range of 1-2 wt%.
According to yet another embodiment of the present invention, a lubricating oil composition comprising of a base oil combination comprising 30-40 wt% solvent refined Group I mineral base oil of kinematic viscosity greater than 30 cSt at 100ºC and 60-70 wt% of hydrocracked Group II base oil of kinematic viscosity greater than 10.5 cSt at 100ºC and the additive composition.
Various objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention
OBJECTIVE OF THE INVENTION:
It is the primary objective of the invention to provide the lubricating oil composition which possesses unique combination of additives and base oil components which can meet the criteria for UTTO type tractor hydraulic lubricant.
It is the further objective of the invention to provide the base oil composition of suitable viscosity which can be used in lubricating oil composition to meet the criteria for UTTO type tractor hydraulic lubricant.
It is the further objective of the invention to provide an additive composition which can be used in lubricating oil composition to meet the criteria for UTTO type tractor hydraulic lubricant.
The objects and features of the present invention will be better understood from the following detailed description taken in conjunction with the Tables.
DETAILED DESCRIPTION OF THE INVENTION:
While the invention is susceptible to various modifications and/or alternative processes and/or compositions, specific embodiment thereof has been shown by way of example in tables and will be described in detail below. It should be understood, however that it is not intended to limit the invention to the particular processes and/or compositions disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the invention as defined by the appended claims.

The tables and protocols have been represented where appropriate by conventional representations, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

The following description is of exemplary embodiments only and is not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention.
The following terms will be used throughout the specification and will have the following meaning unless otherwise indicated:
Viscosity index (VI) is an arbitrary measure for the change of viscosity with variations in temperature. The lower the VI, the greater the change of viscosity of the oil with temperature and vice versa. It is used to characterize viscosity changes with relation to temperature in lubricating oil.
“Pour point” is the temperature at which it becomes semi solid and loses its flow characteristics.
“Flash Point” is the lowest temperature at which vapors of a fluid will ignite.
“TBN” is a measure of a reserve alkalinity of a lubricant. The test is relevant to internal combustion engines due to the acidic byproducts of combustion generated when gasoline and diesel fuel are burned.
“TAN” is a measurement of acidity that is determined by the amount of potassium hydroxide in milligrams that is needed to neutralize the acids in one gram of oil.
“Group I base oil” is Group I base oils are solvent-refined and are classified as less than 90 percent saturates, greater than 0.03 percent sulfur and with a viscosity-index range of 80 to 120.
“Group II base oil” is Group II base oils are defined as being more than 90 percent saturates, less than 0.03 percent sulfur and with a viscosity index of 80 to 120. They are often manufactured by hydrocracking, which is a more complex process than what is used for Group I base oils.
According to one embodiment of the present invention, there is provided a lubricating oil composition which comprises a specific base oil combination of 30-40 wt % of high viscosity solvent refined Group I mineral base oil of kinematic viscosity > 30 cSt at 100ºC and 60-70 wt % of hydro cracked Group II base oil > 10.5 cSt at 100ºC.
According to one embodiment of the present invention, the base oils may be derived from natural resources or synthetic. Mineral oils are used as the base oil in this invention, which includes, for example, paraffinic, naphthenic and other oils, without any limitations whatsoever that are ordinarily used in lubricating oil compositions.
According to one embodiment of the present invention an additive composition comprising of a dispersant olefin copolymer (DOCP) as viscosity index improver in the range of 2-3 wt%, a universal tractor transmission oil (UTTO) additive system in the range of 4-10 wt%, a sulphur phosphorus additive component in the range of 0.5 to 2.5 wt%, and a monounsaturated omega-9- fatty acid in the range of 1-2 wt%.
According to one of preferred embodiment of the present invention the additive composition further comprising of a pour point depressant (PPD) additive, an antifoam additive, a metal deactivator, or/and an additive having sufficient water handling characteristics ranging from 0.8 to 5wt % of water.
According to one embodiment of the present invention the PPD additives may typically be, not limited to, polymeric materials of high molecular weight and include polymethacrylate, polyalkylmethacrylate, alkylated naphthalene, vinyl acetate-fumarate copolymers, polyarylamides, condensation products of haloparaffin waxes and aromatic compounds, wax alkylated phenols, vinyl carboxylate polymer, and terpolymers of dialkylfumarates, vinyl esters of fatty acids and allyl vinyl ethers.
According to one embodiment of the present invention the UTTO additive system is a combination of over based detergent with a TBN of 80-150 mg KOH/gm, zinc dialkyl dithio phosphate, antioxidant component and a polyisobutylene type thickener.
According to one embodiment of the present invention the detergents may be, but not limited to, alkali or alkaline earth metal phosphonates, phenates and sulphonates.
According to one embodiment of the present invention the viscosity modifiers may include, but not limited to, polyisobutylenes, polymethacrylates, polyacrylates, ethylene propylene copolymers, styrene-isoprene/Maleic ester copolymers, hydrogenated styrene, isoprene butadiene copolymers.
According to one embodiment of the present invention the sulphur phosphorus additive may include, but not limited to, combination of sulphurised isobutylene, alkyl thiophosphates, alkyl phosphates, olefins.
According to one embodiment of the present invention the lubricating oil composition of the present invention possesses drain potential of 800 – 1400 hrs.
According to one embodiment of the present invention the lubricating oil composition may also include a minimum concentration of antifoam additives and corrosion inhibitors as defoamant and yellow metal protection additives.
According to one embodiment of the present invention the antifoam additives may include, but not limited to, silicone polymers, acrylic polymers etc. Likewise, the metal deactivators may include, but not limited to, triaryl phosphites, sulphur compounds, diamines, dimercapto thiadiazole derivatives, benzotriazoles.
According to one embodiment of the present invention, the lubricating oil composition comprising of a base oil combination comprising 30-40 wt% solvent refined Group I mineral base oil of kinematic viscosity greater than 30 cSt at 100ºC and 60-70 wt% of hydrocracked Group II base oil of kinematic viscosity greater than 10.5 cSt at 100ºC and the additive composition.
According to one of preferred embodiment of the present invention, the base oil is present in the range of 80-95 wt% and the additive composition is present in the range of 5-15 wt% in the lubricating oil composition.
According to one embodiment of the present invention the lubricating oil composition of the present invention can be used as universal tractor transmission oil (UTTO).
Additional objects and advantages of the disclosure will be set forth in part in the description which follows, and/or can be learned by practice of the disclosure.
It is to be understood that both the foregoing general description and the following description are exemplary and explanatory only and are not restrictive of the disclosure.
The below Table 1 lists the components of lubricating oil composition:
Components Example 1 (Candidate composition)
(wt.%) Example 2

(wt.%)
Base Oil (Solvent Refined Mineral base Oil) 25-35 20-30
Base Oil (Hydrocracked Mineral Base Oil) 40-55 45-55
UTTO additive (combination of over based phenate detergent with a TBN of 80-150 mgKOH/gm, zinc dialkyl dithio phosphate, antioxidant component and a polyisobutylene type thickener) 5-10 4-10
Viscosity Index Improver (VII) Dispersant olefin copolymer) 1-5 0-2
S&P (Additive combination of sulphurised isobutylene, alkyl thiophosphates and alkyl phosphates) 0-2 0-3
Friction Modifier (Monounsaturated omega-9- fatty acid ) 0-2 0-2
PPD(A Polymethacrylate component) 0-2 0-2
Defoamer(Silicone Type) 0-1 Nil
Corrosion Inhibitor (2,5-dimercapto-1,3,4-thiadiazole derivative) Nil 0-2
Table 1
The below Table 2 lists the physicochemical data of the candidate composition (Example 1):
1 KV 100, cSt 11.75
2 KV 40,cSt 93.7
3 VI 115
4 Density,gm/cc 0.8868
5 BF at -18 ºC 8350
6 Pour Point, ºC -33
7 Flash Point, ºC 220
8 Copper strip corrosion at -150 ºC 1
9 TBN, mgKOH/gm 8.52
10 TAN,mgKOH/gm 2.1
11 Foaming Tendency/stability 10/nil,20/nil,10/nil
Table 2

The below Table 3 lists the performance data of the candidate composition (Example 1):
S.No. Characteristics Candidate oil
1 Weld Load, IP-239, kg 250
2 Film Thickness
at 100 0C, 20N, nm
256
3 FZG Load Stage Test 9th stage pass
4 KRL Shear Stability, 20 hrs Stay in grade
5 Water Tolerance ASTM D4997, 0.8% 1% 3% 5%
after test final volume solids, ml nil nil nil nil
after test final volume of water, ml 0 0 0 1
after test final volume emulsion, ml 100 100 100 99
after test final volume oil, ml 0 0 0 0
after test metal constituent loss, ml nil nil nil nil
Table 3
Water Tolerance
Water Tolerance has been done as per ASTM D4997-89 (Test Methods for Evaluation of Water Sensitivity of Multi-Purpose Power Transmission Fluids, Withdrawn 1995). The tractor lubricant composition was mixed with water in a high speed blender, mixture is stored for seven days in a 100 ml centrifuge tube and then the sample is centrifuged to determine the separation in the oil. Loss of additive can also be determined by chemical analysis of the oil phase for loss of metallic constituents of the additive.
Procedure:
199.2 ml of oil and 0.8 ml of distill water is mixed in a blender at 13000±1000 rpm for 60±5 seconds. 100 ml of this mixture is immediately transferred to a clean, dry, conical type centrifuge tube. The tube is stoppered with a clean, dry cork and kept upright in a light free chamber for seven days. After seven days, tube is remove from the chamber and sample is centrifuged for 60±1 min at a relative centrifugal force of 950±50 rcf. Following equation has been used to calculate the centrifugal speed (in rpm) needed to obtain 950±50 rcf at the tip of the tube: RPM=1333.6 rcf/d[d=diameter of swing in mm]. At the end of test % vol of solids, free water and emulsion in the test sample and percent additives separation after centrifugation is reported. The oil phase is also analyzed for loss of metallic constituents of the additives separation after centrifugation. Data for the candidate tractor oil composition have been presented in Table 3.
Shear Stability
KRL tapered bearing shear test gives better differentiation among shear stable polymers and has been used to check the mechanical shear strength of candidate formulation. This test fills the gap between older shear tests (Orbahn and Sonic) and the demanding real world of gear lubricants. 20-hour CEC L-45-T-93 shear test provides the best correlation to actual field performance when compared to other industry shear tests. During this test, the lubricant is tested in a taper bearing fitted into a Four-Ball EP test machine. The taper roller bearing runs submerged in 40 mL of lubricant at constant speed and load at 60ºC for a defined number of motor revolutions or running period.
The following test conditions are employed for performing shear stability test on lubricating oil composition of the present invention:
Temperature: 60 +/-1oC
Speed: 1475 +/- 25 rpm
Duration: 20 hours
Load: 5000 +/- 200 N (510 +/- 20 kgf)
The shear results of candidate composition have been presented in Table 3.
Weld Load IP-239
This test is done on candidate as per IP-239 test standard. The extreme pressure and anti-wear properties of lubricating fluids and greases are determined by Four ball method. This standard specifies procedures for the measurement of the load carrying, anti-friction and anti-wear properties of lubricating oils and fluids and lubricating greases by means of the four ball machine. The Four-Ball EP Test measures a lubricant’s extreme pressure properties under High Hertzian contact in pure sliding, or pure rolling, motion. The test is used to determine the load carrying properties of a lubricant at high test loads. The Falex Four-Ball EP Test rotates a ½- inch diameter ball in contact with three similar balls held stationary in the test cup. The contact surfaces are covered with test lubricant, a load is applied and a timed test is performed. Normally, the wear scars on the three lower balls are measured and averaged. The test is generally terminated at the load where the rotating ball ‘welds’ to the three stationary balls. The Load-Wear Index (LWI) quantifies the wear protection at increasing loads. The Last Non-Seizure Load (LNSL) indicates the transition from elastohydrodynamic to boundary lubrication and metal to metal contact. The load carrying capability of tractor lubricant composition is found satisfactory and the same is reflected in Table 3.
The below Table 4 lists the performance data of the candidate composition (example 1). The candidate composition is tested against John Deere reference standards defined in JDQ 96 standard Test procedure.
S.No. JDQ 96 John Deere Wet Brake Test Candidate Reference 1 Reference 2 Reference 3 Reference 4 Reference 5
1 Torque variation after 1000 cycles, Nm 21908 160449 172283 179529 179251 164630
2 Torque Capacity, Nm 3,25,198 329975 327258 325464 325990 345076
Table 4 : JDQ 96 DATA
Description of Performance Data
The combination of lubricating oil components of the present invention provides following technical performance benefits:
Low Temperature Ability
Brookfield viscosity determines a wide range of viscosities from 1 to 105 P under a low shear rate of shear (up to 102 sec-1). ASTM D 2983 uses temperatures between -5 and -40 ºC. The candidate of the present invention shows exceptional low temperature viscosity results (< 9000cP) at -18 ºC under the test conditions of ASTM D 2983.
Brake Chatter: JDQ 96 Test Available at SWRI, USA
The objective of this procedure is to assess the effect of the oil on brake noise and brake capacity compared to demonstrated with a reference. This procedure covers John Deere JDM J20 and JDM J27.Fluid capability w.r.t. tractor brake chatter, capacity, and durability is evaluated in JDQ-96 1400 test series. For these tests, a John Deere 4640 tractor with a modified power shift transmission is used to drive a John Deere 1400 series industrial axle equipped with annular wet disc brakes. The brake chatter test consists of 30,000 brake engagements. After 1,000, 10,000, 20,000, and 30,000 brake engagements, a series of brake chatter tests is performed at different wheel speeds, brake pressures, and brake temperatures. The lubricant is evaluated at oil temperatures of 32, 49, 60 and 71 ºC. Relative brake capacity and torque variation is summed from all of measurements at each temperature to get an overall relative capacity and torque variation. These results are compared to a known fluid established by John Deere as a lubricant with an acceptable level of chatter. Passing chatter criteria is given in % relative to reference oil in torque variation as described in JDQ 96 procedure. A result of 100% would be equal to the result of reference oil. A result of less than 100% is better than the reference oil in that there is less noise and less chatter. A result of greater than 100% would be worse than the reference oil, indicating more noise and more chatter. The results are presented at Table No. 4.
Data Interpretation
The capacity for each engagement is the average torque during the middle of the engagement. The torque variation is the greatest difference between the maximum and minimum torque recorded during any 0.2 second portion of the engagement. The candidate results can be compared to the baseline reference average. The current reference baseline average is the average of five most recent results. Table 4 contains chatter test results from 1000 cycles.
Torque capacity gives indication of brake capacity and torque variation gives indication of brake noise. The lubricating oils of the present invention show equivalent brake capacity in comparison to reference fluid. Further, lubricating oil of the present invention shows torque variation lower than reference fluid, this shows less brake chatter than reference fluid thus quiet brake operation in comparison to reference fluid.
The below Table 5 lists the performance data of the candidate composition (example 1) in agricultural tractors. The candidate composition is tested against two references. The noise is measured by Noise Meter (DB Meter).
S.No. Candidate
(Example 1) Reference 1
(Example 2) Reference 2 (Market General UTTO Oil)
1. Manual recording No Noise observed during braking –LHS&RHS Very low noise observed during braking -LHS Noise observed during braking LHS&RHS
2. Average Decible Meter reading Observed 90.2 95.7 99
Table 5

The below Table 6 lists the on field noise data of the candidate composition (example 1) in tractors:
Unit Running Hrs Remarks
Tractor No.1 1029 No Noise observed
Tractor No.2 490 No Noise observed
Tractor No.3 497 No Noise observed
Tractor No.4 618 No Noise observed
Tractor No.5 454 No Noise observed
Tractor No.6 1400 No Noise observed
Tractor No.7 399 No Noise observed
Tractor No.8 103 No Noise observed
Table 6
For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained and / or the precision of an instrument for measuring the value. Furthermore, all ranges disclosed herein are inclusive of the endpoints and are independently combinable. In general, unless otherwise indicated, singular elements may be in the plural and vice versa with no loss of generality.
,CLAIMS:We Claim:
1. A base oil combination comprising 30-40 wt% solvent refined Group I mineral base oil of kinematic viscosity greater than 30 cSt at 100ºC and 60-70 wt% of hydrocracked Group II base oil of kinematic viscosity greater than 10.5 cSt at 100ºC.
2. An additive composition comprising of:
(a) a dispersant olefin copolymer (DOCP) as viscosity index improver in the range of
2-3 wt%;
(b) a universal tractor transmission oil (UTTO) additive system in the range of 4-10
wt%;
(c) a sulphur phosphorus additive component in the range of 0.5 to 2.5 wt%; and
(d) a monounsaturated omega-9- fatty acid in the range of 1-2 wt%.
3. The Additive composition as claimed in claim 2, further comprising of a pour point depressant (PPD) additive, an antifoam additive, a metal deactivator, or/and an additive having sufficient water handling characteristics ranging from 0.8 to 5wt % of water.
4. The additive composition as claimed in claim 3, wherein the PPD additive is selected from polymeric material of high molecular weight, condensation products of haloparaffin waxes and aromatic compounds, wax alkylated phenols, vinyl esters of fatty acids and allyl vinyl ethers.
5. The additive composition as claimed in claim 4, wherein the polymeric material of high molecular weight is selected from polymethacrylate, polyalkylmethacrylate, alkylated naphthalene, vinyl acetate-fumarate copolymers, polyarylamides, vinyl carboxylate polymer, and terpolymers of dialkylfumarates.
6. The additive composition as claimed in claim 2, wherein the UTTO additive system is a combination of over based detergent with a TBN of 80-150 mg KOH/gm, zinc dialkyl dithiophosphate, antioxidant component and a polyisobutylene type thickener.
7. The additive composition as claimed in claim 2, wherein the viscosity index improver is selected from polyisobutylenes, polymethacrylates, polyacrylates, ethylene propylene copolymers, styrene-isoprene/Maleic ester copolymers, hydrogenated styrene, isoprene butadiene copolymers.
8. The additive composition as claimed in claim 2, wherein the sulphur phosphorus additive component is a combination of sulphurised isobutylene, alkyl thiophosphates and alkyl phosphates.
9. The additive composition as claimed in claim 3, wherein the antifoam additives is selected from silicone polymers, acrylic polymers.
10. The additive composition as claimed in claim 3, wherein the metal deactivators is selected from triaryl phosphites, sulphur compounds, diamines, dimercapto thiadiazole derivatives and benzotriazoles.
11. A lubricating oil composition comprising of:
(a) a base oil combination comprising 30-40 wt% solvent refined Group I mineral base oil of kinematic viscosity greater than 30 cSt at 100ºC and 60-70 wt% of hydrocracked Group II base oil of kinematic viscosity greater than 10.5 cSt at 100ºC; and
(b) the additive composition as claimed in any of the preceding claims 2-10.
12. The lubricating oil composition as claimed in claim 11, wherein the base oil is present in the range of 80-95 wt% and the additive composition is present in the range of 5-15 wt%.
13. The lubricating oil composition as claimed in claim 11 or 12, whenever used as universal tractor transmission oil (UTTO).